Commentary: Paco Underhill has spent the past 20 years studying shoppers the way Jane Goodall studies chimpanzees. Underhill and his company, Envirosell, spend hours tracking shoppers at department stores, drug stores and malls, watching as they browse, shop and buy. In his book Why We Buy: The Science of Shopping, Underhill reveals some of the tidbits he’s picked up over the years analysing stores for retailers. For instance, almost everyone turns to the right when entering a store, whether or not they’re right-handed. Underhill’s measured things like the "butt-brush" factor: if aisles are too close and a shopper gets bumped from behind, the shopper will move elsewhere. And my favorite tidbit: the more time you spend in a store, the more likely you are to buy. But a woman accompanied by a man will spend even less time in a store than a woman accompanied by a toddler. Essentially Underhill's looking at the science of merchandising –- the process by which a store convinces you not just to look at that widget on a shelf, but to pick it up and buy it. That’s something that mass-market retailers spend years and millions of dollars on -– and something that many feel online retailers have not gotten down yet. "Shopping can be a very sensual activity," Underhill said in an email interview. "It is one of the enjoyable aspects of shopping: feeling, smelling and physically experiencing what you are going to buy." Obviously you can’t do that online. So while online stores don’t have a problem selling to people who already know what they want to buy, or selling products that don’t require sampling (like toner cartridges), they face a much more difficult challenge in appealing to a browser. Online stores do have some advantages, Underhill said –- it's easy to provide limitless product information, and there are no lines or crowds. "A major downfall, however, is that many of these shopping models are geared toward suburban locations where deliveries can be left on the front stoop or someone will be home to accept it. For those of us who don¹t live in Ozzie-and-Harriet-ville, deliveries can become a bit of a problem," he said. That’s why Underhill expects online/offline partnerships to be more successful than pure-plays. Several companies have already started down this path -– Amazon.com recently linked up with Toys R Us, for example, and many retail chains have an online branch. "I envision a combination between online and brick-and-mortar stores where you can get information about what you want online, place your order online, and then pick it up at your nearest location and perhaps throw in a couple of impulse items as well," he said. "This combines the convenience of online shopping with the immediate gratification of being able to have it the same day." Another advantage is that the store gets another chance to target you for impulse purchases. Some stores are already experimenting with that model –- Circuit City, CVS and Best Buy already allow customers to place orders for some products online and pick them up in the stores. It's interesting to note that those stores already had a form of pick and pack in place –- for the consumer electronics stores, it's the electronic equivalent of those little slips you hand to an employee, who then goes out to the warehouse to get your toaster oven or stereo. But Underhill believes that most stores have not gone far enough. "The only problem is that these new channels are separate and often have little to do with the actual stores. What retailers need to do with this new technology is to have the Web site drive business to the physical store, and the physical store drive business to the Web site," he said. "Retailers have to start getting creative in how they combine brick-and-mortar stores and online sites, and I think the best is yet to come." For now, Underhill sees business-to-business companies as the ones best poised to take advantage of the Internet. "When you talk about individual sales, things get much more complicated. How and what we buy is driven by a complex matrix of issues and requirements," he said. "Online shopping probably has not taken off quite as predicted because it does not fulfill some of the requirements we have come to love with shopping such as the sensual aspects or the social aspects." "What is cool and what works are often two different things. Over the past two months I¹ve bought through the Web at Amazon. Only books ­- every time I¹ve tried to buy other stuff ­ they¹ve screwed up. I use Walmart.com for simple gifts -- the site is clumsy, but it works. I tried to buy a car over the Web using Autobytel.com and had an awful experience. There the site was interesting, but the follow-through was a problem and the end result cost me thousands of dollars and many headaches," he added. But Underhill ended on a high note: "I own a f**ked company T-shirt. The order and delivery were seamless. There is hope." See ZDII for US tech investor news. See techTrader for more technology investment news, plus quotes and research. To have your say online click on the TalkBack button and go to the ZDNet News forum. What do you think? Tell the Mailroom. And read what others have said.